Mix crushed Oreo cookies with melted butter until the crumbs look evenly coated, then press firmly into the bottom of a 9-inch springform pan so it forms a compact layer. Freeze for 15 minutes, until the crust feels set.

Spread slightly softened vanilla ice cream in an even layer over the Oreo crust and smooth the top to cover completely. Freeze for 1 hour until firm, with the surface no longer soft.

Drizzle slightly cooled hot fudge sauce over the vanilla layer in a thin ribbon pattern, then lightly smooth only if needed to distribute it. Freeze for 15 minutes to set the fudge.

Spread slightly softened strawberry ice cream over the fudge layer, smooth the top, and cover with plastic wrap to prevent freezer burn. Freeze for at least 4 hours or overnight until fully firm.

Run a warm knife around the edge, release the springform pan, and transfer the cake to a serving plate. Use a clean, steady lift to keep the edges intact.

Pipe whipped topping swirls around the top edge, then scatter rainbow or patriotic sprinkles across the center for color. Slice with a hot knife and serve immediately, showing the distinct Oreo, vanilla, fudge, and strawberry layers.